This invention relates generally to information signal recording and reproducing apparatus and, more particularly, is directed to a video tape recorder which provides different amounts of recording and reproducing time on a magnetic tape.
Video tape recorders (VTR) which record information signals, such as video and/or audio signals, on a magnetic tape which is contained within a cassette, are well-known in the art. With such VTRs, it has been proposed to provide different amounts of recording and reproducing time for the same length of magnetic tape within the cassette. In this regard, it has been proposed to use a hierarchy system of sampling frequencies for an information signal. For example, where the information signal is a color video signal having a luminance component and red and blue color difference signal components, the sampling frequencies of the luminance component, red color difference signal component and blue color difference signal component can be selected as 4f.sub.0, 2f.sub.0 and 2f.sub.0, where 4f.sub.0 is a predetermined frequency, for example, 13.5 MHz. In such case, the relationship between the sampling frequencies of the luminance component, red color difference signal component and blue color difference signal component is 4:2:2. In other words, for the 4:2:2 system, the sampling frequency of the color video signal is 8f.sub.0. If it is desired to reduce tape consumption and thereby increase the recording and reproducing time on the magnetic tape, the sampling frequencies of the luminance component and red and blue color difference signal components may be selected as 2f.sub.0, f.sub.0 and f.sub.0, respectively, that is, the relationship between the sampling frequencies is selected as 2:1:1. Thus, for the 2:1:1 system, the sampling frequency of the color video signal is 4f.sub.0. In such case, it is to be appreciated that the circuitry necessary for the 2:1:1 system need be less complicated than that for the 4:2:2 system, thereby reducing the cost of the apparatus. It is to be further appreciated that the speed of rotation of the rotary magnetic heads of the VTR, the speed of movement of the magnetic tape past the heads and the operating frequency of the processing circuitry generally varies with the hierarchy system utilized, that is, the 4:2:2 system, the 2:1:1 system and other systems. It is therefore to be appreciated that when the speed of movement of the magnetic tape changes so as to change the recording and reproducing time, similar changes should also occur with respect to the rotational speed of the magnetic heads, the operating frequency of the different circuitry, whereby to also change the sampling frequency of the information signal, for both recording and reproduction.